1. Field of The Invention
The present invention relates to a process for producing a printed circuit board.
2. Discussion of Related Art
For producing the conventional printed circuit board by etching the copper foil of a copper-clad laminate to form a desired printed circuit, the subtractive process is known, in which an etching resist is applied to only such portions of the copper foil of the copper-clad laminate as required to form a conductor pattern by printing or photography, followed by removal of the other portions of the copper foil by etching to thereby form the circuit of the conductor on the insulating substrate.
In the above conventional subtractive process, the etching resist covering the thus formed circuit pattern of the conductor is stripped off to expose the copper foil so that the circuit is completed. Thereafter, it is preferred that a solder layer having a thickness of 1 to 2 .mu.m be disposed at land areas of the conductor circuit in order to ensure soldering of electronic components thereupon while preventing oxidation of the copper foil. Thus, generally, the soldering of electronic components requires additional steps comprising applying a solder resist to the conductor circuit after the formation thereof on the insulating substrate and disposing a solder layer on the land areas of the conductor circuit.